It tells the story of a man (played by Tony Leung) and a woman (Maggie Cheung) whose spouses have an affair together and who slowly develop feelings for each other.
The infamous Aunt Mei (Bai Ling), a former gynecologist who performed abortions, makes dumplings with miraculous youth-restoring abilities. Mrs. Li (Miriam Yeung), a former actress desperate to make her womanizing husband (Tony Leung Ka Fai) pay attention to her again, initially refuses to eat them. However, after discovering their potency, she offers to pay Mei any price for more. Things are complicated when Mei is forced to flee the country and the dumplings' power begins to fade.
Idealistic police cadet Chan Wing-Yan (Tony Leung) is recruited by Police Superintendant Wong (Anthony Wong) to go deep undercover as a member of the criminal Triad society. Into the same cadet class, crime boss Hon Sam (Eric Tsang) installs new Triad member Lau Kin Ming (Andy Lau) to become a long-term mole for the gang. A decade later, both have risen through the ranks in their respective aliases -- but when both of their covers are in danger of being blown, a game of life and death ensues.
After his father abandons the family, Autumn Moon (Sam Lee) drops out of high school and becomes a money collector for organized criminals the Triads. On his rounds, he meets and falls in love with Ping (Neiky Yim Hui-Chi), a daughter of one of the Triads' debtors. She is suffering from a fatal kidney disease, and to pay for her medical expenses, Autumn Moon takes an assassination contract, but as he slips deeper into the criminal underworld, he's haunted by a figure from his past.